[dpdk-dev] [PATCH v6 2/8] eal: add common time structures and functions

Pablo de Lara pablo.de.lara.guarch at intel.com
Thu Nov 12 13:55:32 CET 2015


From: Daniel Mrzyglod <danielx.t.mrzyglod at intel.com>

Add common functions and structures to handle time, and cycle counts
which will be used for PTP processing.

Signed-off-by: Daniel Mrzyglod <danielx.t.mrzyglod at intel.com>
Signed-off-by: Pablo de Lara <pablo.de.lara.guarch at intel.com>
Reviewed-by: John McNamara <john.mcnamara at intel.com>
---
 lib/librte_eal/common/Makefile           |   2 +-
 lib/librte_eal/common/include/rte_time.h | 210 +++++++++++++++++++++++++++++++
 2 files changed, 211 insertions(+), 1 deletion(-)
 create mode 100644 lib/librte_eal/common/include/rte_time.h

diff --git a/lib/librte_eal/common/Makefile b/lib/librte_eal/common/Makefile
index 0c43d6a..8508473 100644
--- a/lib/librte_eal/common/Makefile
+++ b/lib/librte_eal/common/Makefile
@@ -40,7 +40,7 @@ INC += rte_string_fns.h rte_version.h
 INC += rte_eal_memconfig.h rte_malloc_heap.h
 INC += rte_hexdump.h rte_devargs.h rte_dev.h
 INC += rte_pci_dev_feature_defs.h rte_pci_dev_features.h
-INC += rte_malloc.h
+INC += rte_malloc.h rte_time.h
 
 ifeq ($(CONFIG_RTE_INSECURE_FUNCTION_WARNING),y)
 INC += rte_warnings.h
diff --git a/lib/librte_eal/common/include/rte_time.h b/lib/librte_eal/common/include/rte_time.h
new file mode 100644
index 0000000..33f3038
--- /dev/null
+++ b/lib/librte_eal/common/include/rte_time.h
@@ -0,0 +1,210 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2015 Intel Corporation. All rights reserved.
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#define NSEC_PER_SEC 1000000000L
+
+/**
+ * @internal
+ *
+ * Structure to hold the parameters of a running cycle counter to assist
+ * in converting cycles to nanoseconds.
+ */
+struct rte_timecounter {
+	/** Last cycle counter value read. */
+	uint64_t cycle_last;
+	/** Nanoseconds count. */
+	uint64_t nsec;
+	/** Bitmask separating nanosecond and sub-nanoseconds. */
+	uint64_t nsec_mask;
+	/** Sub-nanoseconds count. */
+	uint64_t nsec_frac;
+	/** Reads the current cycle counter value. */
+	uint64_t (*read)(void *arg);
+	/** Bitmask for two's complement subtraction of non-64 bit counters. */
+	uint64_t cc_mask;
+	/** Cycle to nanosecond divisor (power of two). */
+	uint32_t cc_shift;
+	/** Argument of read() function pointer. */
+	void *arg;
+};
+
+/**
+ * @internal
+ *
+ * Initialize the rte_timecounter structure.
+ */
+static inline void
+rte_timecounter_init(struct rte_timecounter *tc, uint64_t start_time)
+{
+	tc->cycle_last = tc->read(tc->arg);
+	tc->nsec = start_time;
+	tc->nsec_mask = (1ULL << tc->cc_shift) - 1;
+	tc->nsec_frac = 0;
+}
+
+/**
+ * @internal
+ *
+ * Converts cyclecounter cycles to nanoseconds.
+ */
+static inline uint64_t
+rte_cyclecounter_cycles_to_ns(uint64_t cycles, uint64_t *frac,
+			      uint32_t shift, uint64_t mask)
+{
+	uint64_t ns;
+
+	/* Add fractional nanoseconds. */
+	ns = cycles + *frac;
+	*frac = ns & mask;
+
+	/* Shift to get only nanoseconds. */
+	return ns >> shift;
+}
+
+/**
+ * @internal
+ *
+ * Similar to rte_cyclecounter_cycles_to_ns(), but this is used when computing
+ * a time previous to the time stored in the cycle counter.
+ */
+static inline uint64_t
+rte_cyclecounter_cycles_to_ns_previous(uint64_t cycles, uint64_t frac,
+				       uint32_t shift)
+{
+	return ((cycles - frac) >> shift);
+}
+
+/**
+ * @internal
+ *
+ * Converts cycle units into nanoseconds and adds to the previous time stored.
+ */
+static inline uint64_t
+rte_timecounter_cycles_to_ns_time(struct rte_timecounter *tc,
+				  uint64_t cycles)
+{
+	uint64_t delta;
+	uint64_t nsec = tc->nsec;
+
+	delta = (cycles - tc->cycle_last) & tc->cc_mask;
+
+	if (delta > (tc->cc_mask / 2)) {
+		/* Handle cycle counts that have wrapped around . */
+		delta = (tc->cycle_last - cycles) & tc->cc_mask;
+		nsec -= rte_cyclecounter_cycles_to_ns_previous(delta,
+							       tc->nsec_frac,
+							       tc->cc_shift);
+	} else {
+		nsec += rte_cyclecounter_cycles_to_ns(delta,
+						      &tc->nsec_frac,
+						      tc->cc_shift,
+						      tc->nsec_mask);
+	}
+
+	return nsec;
+}
+
+/**
+ * @internal
+ *
+ * Get nanoseconds since the last call to this function.
+ */
+static inline uint64_t
+rte_timecounter_read_ns_delta(struct rte_timecounter *tc)
+{
+	uint64_t cycle_now, cycle_delta;
+	uint64_t ns_offset;
+
+	/* Read cycle counter. */
+	cycle_now = tc->read(tc->arg);
+
+	/* Calculate the delta since the last call. */
+	cycle_delta = (cycle_now - tc->cycle_last) & tc->cc_mask;
+
+	/* Convert to nanoseconds. */
+	ns_offset = rte_cyclecounter_cycles_to_ns(cycle_delta, &tc->nsec_frac,
+						  tc->cc_shift, tc->nsec_mask);
+
+	/* Store current cycle counter for next call. */
+	tc->cycle_last = cycle_now;
+
+	return ns_offset;
+}
+
+/**
+ * @internal
+ *
+ * Read timecounter and update the internal nanosecond count in the structure.
+ */
+static inline uint64_t
+rte_timecounter_read(struct rte_timecounter *tc)
+{
+	uint64_t nsec;
+
+	/* Increment time by nanoseconds since last call. */
+	nsec = rte_timecounter_read_ns_delta(tc);
+	nsec += tc->nsec;
+	tc->nsec = nsec;
+
+	return nsec;
+}
+
+/**
+ * @internal
+ *
+ * Convert from timespec structure into nanosecond units.
+ */
+static inline uint64_t
+rte_timespec_to_ns(const struct timespec *ts)
+{
+	return ((uint64_t) ts->tv_sec * NSEC_PER_SEC) + ts->tv_nsec;
+}
+
+/**
+ * @internal
+ *
+ * Convert from nanosecond units into timespec structure.
+ */
+static inline struct timespec
+rte_ns_to_timespec(uint64_t nsec)
+{
+	struct timespec ts = {0, 0};
+
+	if (nsec == 0)
+		return ts;
+
+	ts.tv_sec = nsec / NSEC_PER_SEC;
+	ts.tv_nsec = nsec % NSEC_PER_SEC;
+
+	return ts;
+}
-- 
1.8.1.4



More information about the dev mailing list